1. Field of the Invention
Various means are available for mechanically smoothing the surfaces of materials. Rotary, vibratory, belt and orbital sanders, have various sanding surface shapes and sizes, and are often used for this purpose. The invention is described in terms of its application to random orbital sanders, rotary sanders, and orbital sanders. However, application to any surfacing machine is included in the field of the invention.
2. Description of Related Art
In the field of surface finishing, workers use various types of powered and manual abrading methods. In most cases, a worker will use replaceable sandpaper pads in conjunction with reciprocating or orbital machines. Generally, these methods produce a satisfactory finish on woods, painted woods, plastics or metals.
A problem faced by such workers is the cost associated with constantly replacing sand paper. These costs can mount both in the expense of the pads and in the time required to replace. The replacement time can be considerable, as workers often must traverse ladders and locate fresh pads. Moreover, as traditional abrading devices wear, they provide variable finish, which is not desirable. For example, a 40-grit sandpaper can start its useful life providing a proper coarse finish. However, the grit level immediately begins to degrade when the pad use begins. The 40-grit might perform like an 80-grit when the replacement time arrives.
The prior art is replete with abrasives attached to flexible sheets. As an example, FIG. 1 illustrates the use of flexible sheets 30 coated with sheet back side 33 on one side with adhesive applied to the sheet back side 33. The flexible sheet 30 attached to the platen 31 of a manually operated or handheld orbital sander 13, which are known in the art of smoothing the surfaces of hard and soft materials. When smoothing soft material surfaces or low melting point surfaces, the sheet back side 33 becomes easily clogged with waste or amorphous material that can not be removed, resulting in premature failure and replacement. When smoothing hard material surfaces the sheet back side 33 often breaks down and loses the ability to remove material from the material surface resulting in premature failure and replacement. When smoothing soft and hard material surfaces simultaneously, i.e. a nail in a piece of wood, the flexible sheet 30 often tears also resulting in premature failure and replacement.
FIG. 2 illustrates advances over that of the flexible sheet 30 art that have addressed convenience and ease of replacement. A flexible sheet of metal 34 has one rough surface 35 and one flat surface having Velcro™ 36 adhesively attached thereto. Velcro™ 36 is also applied to the platen of the manually operated or handheld orbital sander 13. Although this advance addresses the issues of premature failure experienced with the coated flexible sheet 30 art, many performance, effectiveness, productivity, efficiency and convenience issues are not addressed.
Moreover, various attempts have been made in using metallic and other rigid cutters or abrasive discs. By way of example, U.S. Pat. No. 1,411,936 to Salata discloses a filing machine and U.S. Pat. No. 2,043,509 to Easters discloses a metal and wood surfacing tool. (936) to Salata shows only a device for reciprocating a conventional metal file back and forth, and is thus not intended for a random orbital machine. (509) to Easters shows a rotary filing machine which may work on wood. However, the complexity of the roller mechanism will make it susceptible to failure due to debris entering the machine.
A simpler method of facing a surface that alleviates the problems above is to attach files to rotary discs or to form file patterns in rotary discs. By way of example, U.S. Pat. No. 992,437 to Metcalf discloses a rotary file. U.S. Pat. No. 3,086,277 to Hardy discloses an abrasive finishing disk. U.S. Pat. No. 2,768,422 to McKenna discloses a file and method of making the same. U.S. Pat. No. 2,994,942 to Harvell discloses a motor operated vehicle body and fender file. U.S. Pat. No. 4,639,989 to Filby discloses a sanding tool. U.S. Pat. No. 5,056,203 to Miller shows an abrading and cutting tool assembly. U.S. Pat. No. 3,165,813 to Harvell discloses a rotary file. (989) to Filby provides a series of saw type blades on a rotary disc which may be used in conjunction with an orbital sander. However, the sparsely located teeth could not be used to provide a smooth finish on a wood surface. (277) to Hardy and (942) to Harvell show rotary files with replaceable cutters. They do not however, show rotary devices which are used for simultaneous smoothing and cutting. (422) to McKenna, (203) to Miller and (803) to Harvell show rotary files with continuous patterns. These devices cannot however be used to both remove and smooth material simultaneously.
A number of cutters and abraders have been combined with quick fasteners for rapid replacement of worn or damaged tools. By way of example, U.S. Pat. No. 4,423,571 to Selander discloses a quick change shoe assembly for a straight line sander. U.S. Pat. No. 5,967,886 to Wuensch discloses a hand power tool for flat machining. U.S. Pat. No. 5,123,139 to Leppert shows a buffing pad assembly. None of the above devices, however show a finishing plate which when used on a random orbital sander can both remove material and smooth material simultaneously.
To address the need to move an abrading device into a corner, a number of different shapes have been used. By way of example, U.S. Pat. No. 5,398,457 to Updegrave shows an edge and corner sanding attachment. This device, however does not show a hardened steel disc with multiple lines of cutting blades.
To address the shortcomings of traditional abrasive pads, abrasive manufacturers have also developed a number of structured abrasive products. By way of example, U.S. Published Application Number 20070254560 to Woo shows a structured abrasive article. While these systems provide certain benefits over traditional abrasives, they also have certain drawbacks. Since the points are “pyramidal” rather than angled, they cannot be used for simultaneous smoothing and cutting. Moreover, since they are abrasive, they work by way of friction. The same friction which causes the system to work also causes particles to build up, and thereby lose effectiveness. If the system comprised a series of smooth hardened cutting blades, the particle buildup problem could be alleviated because the blade relief surface would provide a low friction channel for debris to escape.